<!DOCTYPE HTML>
<html>
<head>
<meta charset=UTF-8>
<meta name="keywords" content="白菜编辑部">
<title>白菜编辑部</title>
<style type="text/css">
</style>
</head>
<body>
    <table>
        <tr>
            <td>A</td>
            <td>B</td>
            <td>C</td>
        </tr>
        <tr>
            <td>1</td>
            <td>2</td>
            <td>3</td>
        </tr>
        <tr>
            <td>4</td>
            <td>5</td>
            <td>6</td>
        </tr>
    </table>

<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<script type="text/javascript">
    jQuery(function($){
        $('table').append ("<tr></tr>");
        var len = $('table tr:eq(0) td').length;
        for( var i = 0; i < len; i++)
        {
            var sum = 0;
            $('table tr:gt(0) td:nth-child(' + (i + 1) + ')').each (function (j, dom)
            {
                sum += parseFloat ($(this).text ());
            });
            $('table tr:last').append ("<td>" + sum + "</td>");
        }
    });
    $(function () {
 
        var h1 = 0; //第一列的和
 
        var h2 = 0; //第二列的和
 
        var h3 = 0; //第三列的和
 
        var h = 0; //
 
        $("#table1 tr").each(function () {
 
            if (h == 0) {
 
                h++;
 
            }
 
            else {
 
                h1 +=  parseInt($(this).find("td:nth-child(1)").html());
 
                h2 += parseInt($(this).find("td:nth-child(2)").html());
 
                h3 +=  parseInt($(this).find("td:nth-child(3)").html());
 
            }
 
        });
 
        alert(h1);
 
        alert(h2);
 
        alert(h3);
 
    });
 
</script>


</body>
</html>